By Raquel Cunha and Alberto Fajardo
LORETO, Mexico Sept 28 (Reuters) - Hurricane Polo closed in on Mexico's Baja California Sur on Monday evening, threatening its Pacific coastline with destructive wind, flash floods and a storm surge before crossing the peninsula and making a second landfall on the mainland.
At 5 p.m. local time (0000 GMT), the US National Hurricane Center said Polo was set to initially come ashore as a Category 3 hurricane, though the likely strike zone is an area far less populated
than the Los Cabos resort corridor at the southern tip.
The NHC forecast the storm to then cross the Gulf of California and hit southern Sonora state early on Tuesday still at hurricane strength, before weakening rapidly inland.
Residents in the towns in Polo's path packed supermarkets over the weekend to buy water, diapers, milk and other basics before shop owners boarded up shopfronts. Authorities closed beaches on Monday, suspended maritime activity in high-risk areas and opened temporary shelters.
Polo's effects could also reach the United States after landfall. The NHC issued a wind advisory for parts of southern New Mexico and far west Texas into Tuesday night, expecting Polo's remnants to move inland.
The National Weather Service in El Paso said tropical moisture from Polo and earlier Pacific storm Odalys could surge into the US Southwest and central states this week, bringing several days of heavy to excessive rainfall and possible flooding.
General Motors said it suspended production at its Ramos Arizpe assembly plant in Coahuila on Monday because of disruption linked to Polo, and that it expects normal operations to resume on Tuesday.
Trailing behind Polo, Tropical Storm Rachel strengthened slightly off Mexico's southwestern Pacific coast. At 6 p.m. local time (0000 GMT), the NHC said Rachel was about 250 miles (400 km) southwest of resort town Acapulco and 345 miles (555 km) south-southeast of port hub Manzanillo, with maximum sustained winds of 60 mph (95 kph).
It forecast Rachel to crawl offshore along the coast of southwestern Mexico while strengthening into a hurricane by midweek.
(Reporting by Raquel Cunha and Alberto Fajardo in Loreto, Mexico and Aida Pelaez-Fernandez in Barcelona and Paolo Laudani in Gdansk; Additional reporting by Raul Cortes and Ana Isabel Martinez in Mexico City; Writing by Kylie Madry; Editing by Mark Potter, Aurora Ellis and Christopher Cushing)
